The role of cytokinins and thidiazuron in the stimulation of somatic embryogenesis in key members of the Restionaceae

Abstract

Rushes are important understorey species and comprise a significant component of pre-mined ecosystems. Re-establishment of rushes into disturbed sites has often been problematic. Several cytokinins and thidiazuron were investigated for the stimulation of somatic embryogenesis in key members of the Restionaceae. Somatic embryogenesis was observed for Desmocladus flexuosus (R.Br.) B.G.Briggs & L.A.S.Johnson with benzyladenine (BA) at 1, 5 or 15 μM alone and 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D). The response to zeatin (Z) and 2iP-6-γ-γ-dimethyl-allyamino-purine (2iP) was negligible. For Baloskion tetraphyllum (J.J.H. de Labillardiere) B.G.Briggs & L.A.S.Johnson and Lyginia imberbis R.Br., BA, Z and 2iP were ineffective in stimulating any response.Somatic embryogenesis was achieved for B. tetraphyllum on 1/2-strength Murashige Skoog (1/2 MS) + 1 μM 2,4-D, with an estimated 14 000 somatic embryos produced from 1 g of plant material. All somatic embryos converted into plantlets and were successfully transferred to soil.Investigation of thidiazuron (TDZ) at 5 and 10 μM and 1 μM 2,4-D demonstrated that young coleoptiles (5–7 days) of B. tetraphyllum produced significantly more somatic embryos (168-fold more) than did older coleoptiles (>14 days). For D. flexuosus, leaf basal portions produced somatic embryos on 5 and 10 μM TDZ, and 5 μM TDZ + 1 μM 2,4-D. Proliferation of 'secondary somatic embryos' was also successful when somatic embryos were initiated on 10 μM TDZ and transferred to 1/2 MS (~9-fold increase).This study demonstrated variation in response among species of the same family, with D. flexuosus responding to BA and TDZ and B. tetraphyllum responding only to 2,4-D. The protocol investigated has the potential to be commercially viable with over 14 000 somatic embryos produced in 6 weeks for B. tetraphyllum.

Initiation of embryogenic cell suspensions of taro (Colocasia esculenta var. esculenta) and plant regeneration

“…Consequently, the application of very low concentrations of exogenous 2,4-D and TDZ was necessary. Both of these growth regulators have been reported to modulate endogenous auxin (Visser et al 1992;Ribnicky et al 1996;Panaia et al 2004). …”

Involvement of Plant Hormones and Plant Growth Regulators on in vitro Somatic Embryogenesis

“…However, ABA, ethylene, GAs and other hormones have regulatory roles which must not be ignored in culture systems. Moreover, a new generation of PGRs, such as thidiazuron, a CK that belongs to the phenylureas, is emerging as successful alternative for high-frequency direct regeneration of somatic embryos, even from well differentiated explant tissues (Gairi and Rashid 2004a,b;Panaia et al 2004;Zhang et al 2005). Raemakers et al (1995) and Gaj (2004) presented statistics about the number of species that respond to and of protocols that use different PGR groups and combinations to induce SE.…”

Efficiency of SSR markers for determining the origin of melon plantlets derived through unfertilized ovary culture

“…Whereas the control treatment suppressed the ovule growth and ultimately ovary slices turned brown after 2 weeks of culture on the regeneration medium (data not shown). Cytokinins (BAP) are usually incorporated in tissue culture media for cell division and differentiation of adventitious shoots from callus and organs (Panaia et al 2004). The incorporation of BAP at low levels was successfully applied in the present study for embryo maturation and ultimately plantlet regeneration.…”